144 research outputs found

    Secondary flow in contour currents controls the formation of moat-drift contourite systems

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    Ocean currents control seafloor morphology and the transport of sediments, organic carbon, nutrients, and pollutants in deep-water environments. A better connection between sedimentary deposits formed by bottom currents (contourites) and hydrodynamics is necessary to improve reconstructions of paleocurrent and sediment transport pathways. Here we use physical modeling in a three-dimensional flume tank to analyse the morphology and hydrodynamics of a self-emerging contourite system. The sedimentary features that developed on a flat surface parallel to a slope are an elongated depression (moat) and an associated sediment accumulation (drift). The moat-drift system can only form in the presence of a secondary flow near the seafloor that transports sediment from the slope toward the drift. The secondary flow increases with higher speeds and steeper slopes, leading to steeper adjacent drifts. This study shows how bottom currents shape the morphology of the moat-drift system and highlights their potential to estimate paleo-ocean current strength

    A Single E627K Mutation in the PB2 Protein of H9N2 Avian Influenza Virus Increases Virulence by Inducing Higher Glucocorticoids (GCs) Level

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    While repeated infection of humans and enhanced replication and transmission in mice has attracted more attention to it, the pathogenesis of H9N2 virus was less known in mice. PB2 residue 627 as the virulent determinant of H5N1 virus is associated with systemic infection and impaired TCR activation, but the impact of this position in H9N2 virus on the host immune response has not been evaluated. In this study, we quantified the cellular immune response to infection in the mouse lung and demonstrate that VK627 and rTsE627K infection caused a significant reduction in the numbers of T cells and inflammatory cells (Macrophage, Neutrophils, Dendritic cells) compared to mice infected with rVK627E and TsE627. Further, we discovered (i) a high level of thymocyte apoptosis resulted in impaired T cell development, which led to the reduced amount of mature T cells into lung, and (ii) the reduced inflammatory cells entering into lung was attributed to the diminished levels in pro-inflammatory cytokines and chemokines. Thereafter, we recognized that higher GCs level in plasma induced by VK627 and rTsE627K infection was associated with the increased apoptosis in thymus and the reduced pro-inflammatory cytokines and chemokines levels in lung. These data demonstrated that VK627 and rTsE627K infection contributing to higher GCs level would decrease the magnitude of antiviral response in lung, which may be offered as a novel mechanism of enhanced pathogenicity for H9N2 AIV

    Novel materials for solid oxide fuel cells cathodes and oxygen separation membranes: Fundamentals of oxygen transport and performance

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    In the field of modern hydrogen energy, obtaining pure hydrogen and syngas and then being able to use them for green energy production are significant problems. Developing solid oxide fuel cells (SOFC) and catalytic membranes for oxygen separation as well as materials for these devices is one of the most likely ways to solve these problems. In this work, the authors’ recent studies in this field are reviewed; the fundamentals of developing materials for SOFC cathodes and oxygen separation membranes’ permselective layers based on research of their oxygen mobility and surface reactivity are presented. Ruddlesden – Popper phases Ln2–xCaxNiO4+δ (LnCNO) and perovskite-fluorite nanocomposites PrNi0.5Co0.5O3–δ–Ce0.9Y0.1O2–δ (PNC–YDC) were studied by isotope exchange of oxygen with C18O2 and 18O2 in flow and closed reactors. For LnCNO a high oxygen mobility was shown (D* ~ 10–7 cm2/s at 700 °C), being provided by the cooperative mechanism of oxygen migration involving both regular and highly-mobile interstitial oxygen. For PNC–YDC dominated a wide fast diffusion channel via fluorite phase and interphases due to features of the redistribution of cations resulting in superior oxygen mobility (D* ~ 10–8 cm2/s at 700 °C). After optimization of composition and nanodomain structure of these materials, as cathodes of SOFC they provided a high power density, while for asymmetric supported oxygen separation membranes – a high oxygen permeability. © 2020Support of different parts of the work by the Russian Science Foundation (Project 16-13-00112) and the budget project №AAAA-A17-117041110045-9 for Boreskov Institute of Catalysis is gratefully acknowledged. The authors from the Ural Federal University are grateful to the Government of the Russian Federation (Agreement 02.A03.21.0006, Act 211). Ce 0.9 Y 0.1 O 2–δ |Ce 0.9 Gd 0.1 O 2–δ |Ni/Zr 0.84 Y 0.16 O 2–δ anodic half-cells and Ni/Al foam substrates were kindly provided by H.C. Starck, Germany and Powder Metallurgy Institute NAN Belarus, respectively. Authors would like to appreciate International Conference on Advances in Energy Systems and Environmental Engineering (ASEE19, Wroclaw, Poland, June 9-12, 2019) Organization Committee

    Tracing (Theories of) Racism in Sociological Thinking: A Postcolonial Approach.

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    Winkel H. Tracing (Theories of) Racism in Sociological Thinking: A Postcolonial Approach. In: Gärtner JTD, Wilckens MS, eds. Racializing Humankind: Interdisciplinary Perspectives on Practices of `Race´and Racism. Beiträge zur Geschichtskultur. Vol 43. KÜln: BÜhlau; 2022: 33-50
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